Taxonomy through the lens of neutral helium microscopy.

The field of taxonomy is critically important for the identification, conservation, and ecology of biological species. Modern taxonomists increasingly need to employ advanced imaging techniques to classify organisms according to their observed morphological features. Moreover, the generation of three-dimensional datasets is of growing interest; moving beyond qualitative analysis to true quantitative classification. Unfortunately, biological samples are highly vulnerable to degradation under the energetic probes often used to generate these datasets. Neutral atom beam microscopes avoid such damage due to the gentle nature of their low energy probe, but to date have not been capable of producing three-dimensional data. Here we demonstrate a means to recover the height information for samples imaged in the scanning helium microscope (SHeM) via the process of stereophotogrammetry. The extended capabilities, namely sparse three-dimensional reconstructions of features, were showcased via taxonomic studies of both flora (Arabidopsis thaliana) and fauna (Heterodontus portusjacksoni). In concert with the delicate nature of neutral helium atom beam microscopy, the stereophotogrammetry technique provides the means to derive comprehensive taxonomical data without the risk of sample degradation due to the imaging process.